Automatic pool cleaners normally are connected to a source of suction through a flexible pipe that is in turn connected to a suction opening in the base of the pool weir or skimmer which is connected by suitable piping to a circulating pump for the pool. In order that the cleaner and the pipe are not subject to undue negative pressure during operation, the pipe is often connected to the piping through a regulating control valve.
There are a number of such regulating control valves which are known. Typical of such control valves are those described in U.S. Pat. No. 4,643,217; (Frentzel) issued to U.S. Pat. No. 4,368,751 (issued to Chauvier); U.S. Pat. No. 4,790,344 (issued to Chauvier et al) and U.S. Pat. No. 4,570,660 (issued to Chauvier).
This invention is concerned with a regulating control valve which is different to the foregoing and which comprises a main water passage having an inlet port and an outlet port; a relief chamber connected to the main water passage and having an opening remote from the passage; and a closure for the opening, the closure having a relief port therethrough, the surround (i.e., edge) of the relief port comprising a valve seating, and a relief valve within the chamber that is biassed to seat on the valve seating, the relief valve being connected to a surface subject to the suction pressure in the main passage so that when there is excessive suction in the main passage, the relief valve is drawn away from the valve seating against the bias to open the relief port. Such a control valve is hereinafter referred to as "a control valve of the kind set forth".
One widely used prior art control valve of the kind set forth will be described in detail below with reference to FIGS. 2 to 4. In this control valve, the relief valve will normally project at least partially through the relief port. Such a control valve of the kind set forth normally works very satisfactorily. It has been found, however, that when the swimming pool water contains a lot of leaves, these will tend to be caught between the relief valve and the valve seating, so that the relief valve is unable to move freely to relieve the high negative pressure in the main passage.